Big Network's Edge Pro and Edge Lite include multiple high availability features to assist network architects and engineers in achieving Service Level Objectives (SLOs). These capabilities are realized by applying various policies to Wide Area Network (WAN) ports on the Edge Pro and Edge Lite. This article provides an overview of high availability features available.
Local Services - Local Breakout
The Local Breakout service provides a Network Address Translation (NAT) and default gateway virtual function. The Local Breakout function automatically provides Internet failover service to connected clients by using WAN Interface Priority. When you set a WAN Interface Priority, you are providing the Edge Device with an ordered list by preference of which WAN provider to use for Local Breakout Internet Access.
The Big Edge device uses ICMP based probes to determine availability of the WAN according to the ordered list set by WAN Interface Priority. These probes are launched every minute against Cloudflare's DNS Network (126.96.36.199) and Google's DNS Network (188.8.131.52). Should these endpoints go unresponsive to ICMP pings, the next available WAN connection will be selected for Local Breakout traffic.
During an Internet Failover event, the NAT function will remap translations to use the WAN IP address of the next available WAN connection. This will cause a reset of existing sessions due to the change of WAN IP.
Connected Interfaces - Connected Cloud Network
Connecting your Local Network to a Cloud Network enables Big Network's SD-WAN functionality on the Edge Pro and Edge Lite. The SD-WAN functionality creates a full mesh of L2 tunnels across all devices participating in a Cloud Network. For example:
- If you have 2x locations, each with a single ISP, then 1x tunnel will be created (A1 <-> B1).
- If you have 2x locations, each with dual ISPs, then 4x tunnels will be created (A1 <-> B1, A1 <-> B2, A2 <-> B1, A2 <-> B2)
- If you have 3x locations, each with dual ISPs, then 12x tunnels will be created (A1 <-> B1, A1 <-> B2, A1 <-> C1, A1 <-> C2, A2 <-> B1, A2 <-> B2, A2 <-> C1, A2 <-> C2, B1 <-> C1, B1 <-> C2, B2 <-> C1, B2 <-> C2)
Tunnels are created automatically without manual configuration.
Traffic carried via Big Network SD-WAN is carried via all available WAN links (except those marked in "Spare Mode") by using a balanced flow based allocation scheme. Quality of Service (QoS) probes are launched via each path every 250ms to evaluate path availability. Active flows directed to dead paths are automatically re-allocated to live paths.
A WAN port may be marked into "Spare Mode". When in Spare Mode, the WAN will not be used for SD-WAN traffic unless all other non-Spare Mode WAN ports become unavailable based upon WAN monitoring probes to Cloudflare's DNS Network (184.108.40.206) and Google's DNS Network (220.127.116.11) (see Internet Breakout above).
Combining Services - Local Breakout and Connected Cloud Networks
Combining Local Breakout and Connected Cloud Networks functionality is possible, but is an advanced configuration, and outside the scope of this document at this time.